It’s often thought that the ideal currency or exchange rate regime would:

1. Be fixed against the USD;

2. Be convertible to and from USD for traders and investors so there are open goods, services and capital markets, and;

3. Allow independent monetary policy set by the country’s central bank, independent of the US central bank. So the country can set its own interest rate independent of the US Federal Reserve’s USD interest rate.

However, not all of these characteristics can be achieved. One must be sacrificed. This is the 'impossible trinity'.

Which of the following exchange rate regimes sacrifices convertibility?

According to the impossible trinity, a currency can only have two of these three desirable traits: be fixed against the USD; convertible to and from USD for traders and investors so there are open goods, services and capital markets; and allow independent monetary policy set by the country’s central bank, independent of the US central bank.

Which of the following exchange rate regimes sacrifices fixing the exchange rate to the USD? In other words, which regime uses a floating exchange rate?